Bleeding while not on period???

Okay so last night after me and my boyfriend got done with oral, I noticed late that night that I was bleeding just a lil, and it looked like old blood. This morning I woke up and still was bleeding a lil. Nothing to the extent that I need a tampon etc. I’ve been on birth control for over 2 years and always take it on time. And am not on my break week. Back track to NYE and me and my boyfriend though it was a good idea to have sex in a hot tub. It irritated me down there (So before I hear it, yes fucking in the hot tub was dumb, but we were drunk). Could this be why I’m bleeding a little?? Or what?